Data Transmission

ABSTRACT

A communications device ( 1 ) communicates with an access point ( 7 ) to gateway ( 21 ) and local area network ( 13 ) by a wired or wireless communications link ( 9 ). These components may, for example, be accommodated on a train or serve some other predefined area. Gateway ( 21 ) receives data packets from device ( 1 ) representing information for transmission via that device&#39;s “home” communication system ( 15 ) to a destination device. The gateway ( 21 ) creates packet data protocol channels ( 27,29,31 ) with a plurality of communication systems ( 15,23 ) and ( 25 ) and sends the data packets received from the device ( 1 ) selectively over each of these communications channels ( 27,29,31 ). A link between a communications systems ( 23 ) and ( 25 ) allows the data packets to be forwarded to the communications system ( 15 ) where they are compiled by concentrator ( 49 ) for onward transmission. The communication systems ( 15,23,25 ) may be mobile or cellular communications systems.

TECHNICAL FIELD

This invention relates to a method of and apparatus for transmittingdata between devices.

BACKGROUND ART

Systems are known which allow a connection to a user's home cellularnetwork provider in an environment where no dedicated connection to theuser's cellular network provider is available by providing a gatewaywhich is able to offer multiple different technologies (for example,satellite communications and cellular communications). Such systems actto transmit the user data using a chosen one of the technologiesoffered, with the most suitable technology being chosen dependent on thecoverage and quality available.

It is also known to transmit user data from a single terminal to theuser's home cellular network over multiple packet data protocol (PDP)data channels.

DISCLOSURE OF INVENTION

According to the invention there is provided a method of transmittinginformation between a first device and a second device, the methodincluding transmitting respective data packets representing informationfrom one of said devices over different ones of a plurality ofcommunications systems such that the data packets are received by theother of said devices and the information represented thereby may beused.

According to the invention there is also provided apparatus fortransmitting information between a first device and a second device,including means for transmitting respective data packets representinginformation from one of said devices over different ones of a pluralityof communications systems such that the data packets are received by theother of said devices and the information represented thereby may beused.

BRIEF DESCRIPTION OF DRAWINGS

A method of and apparatus for transmitting data will now be described,by way of example only, with reference to the accompanying drawing inwhich:

FIG. 1 is a diagrammatic representation of elements used in theembodiment of the invention;

FIG. 2 is a logical diagram of the IP load balancing method showing thecorresponding protocol stacks;

FIG. 3 is a representation of the IP data packets showing the encryptioncarried out as part of the IPSec tunnelling protocol; and

FIG. 4 is a representation of the IP data packets showing theencapsulation carried out as part of the IPinIP protocol.

In the drawings like elements are designated the same reference numeral.

BEST MODE FOR CARRYING OUT THE INVENTION

One way in which IP data packets could be distributed between a user anda service provider in accordance with the invention is shown in FIG. 1.This drawing shows the system from the service level.

User terminals 1, 3, 5 are able to connect to an access point 7 via anysuitable connection 9 (which for example may be a wireless connectionsuch as a cellular radio connection, Bluetooth connection or infra-redconnection, or may be a connection via a cable). The access point 7 maybe a wireless local area network (WLAN) hot spot, a wireless fidelity(WiFi) access point, or any other access point providing access to aremote communications network. The access point 7 may be provided in amoving environment (for example, on a train) or in a fixed environmentwhere users may wish to access the remote communications network.

The user terminals may, for example, comprise mobile (cellular)telephones, personal digital assistance (PDAs), laptop computers or thelike. It is not essential that the user terminals 1,3 and 5 have thefacility to communicate with a mobile telecommunications network such asa GSM or 3G/UMTS network. If the user terminals 1,3 and 5 do have thisfunctionality they will be provided with a SIM or USIM that allowsauthentication of the device with a mobile telecommunications network inthe known manner. Alternatively, the user devices are provided with anyother means of communication with the access point 7. The user terminalsmay have the facility to use multiple communications media forcommunicating with the access point 7.

In the embodiment to be described each of the user terminals 1,3 and 5are registered with a home cellular telecommunications network 15 toobtain communications services therefrom and to allow connection to aservice provider such as an internet service provider (for example, atrain station or airport). There is no requirement for the userterminals 1,3,5 to be in an area where there is coverage by the homecellular network 15 in order to communicate with the access point 7.

Once a terminal 1, 3, 5 has been connected to the access point 7 it isassigned a random IP address by the Dynamic Host Configuration Protocol(DHCP) server 11 of the local area network (LAN) 13 that may be providedin the specific environment (for example, on board a train, at a trainstation or at an airport) of the access point 7. Communications betweenthe access point 7 and the LAN 13 are routed via gateway transmitter(BGW-T) 21, to be described in further detail later. The user of any ofthe terminals 1, 3, 5 is at that point able to access any servicesavailable on a local intranet provided within the specific environment.

If the user of any of the terminals 1, 3, 5 requires access to theirhome cellular network 15 and the services provided by their homecellular network operator, the terminal 1, 3, 5 is authenticated withthe network. Authentication may be provided between the AAA(Authentication, Authentication and Accounting) proxy server 17 of theLAN 13 and the AAA proxy server 19 of the user's home cellular network15. It is preferable for this authentication to be SIM- or USIM-based(using the SIM or USIM associated with the relevant terminal 1,3,5) butcould also be provided by any suitable alternative authenticationprocedure, such as a username/password scheme. For example, if theauthentication is SIM-based (that is, a user terminal is authenticatedusing data stored on a SIM associated with—and typically housedwithin—that terminal) the authentication will be performed by exchangeof data between the user terminal 1,3,5 and the AAA proxy server 17 (viaintermediate components shown in FIG. 1) and in turn by an exchange ofdata between the AAA proxy server 17 and the AAA proxy server 19 of theuser's home cellular network (again via the intermediate componentsshown in FIG. 1, to be described in more detail later). For example, AAAproxy server 19 may send a random challenge to the AAA proxy server 17,which is transmitted to the SIM of the relevant terminal. The SIMresponds by encrypting the random challenge using both an authenticationalgorithm and a unique key Ki resident within the SIM and previouslyassigned to that particular SIM by the home network 15. The encryptedresponse of the SIM is transmitted by the terminal to the AAA proxyserver 17, and from there to the AAA proxy server 19. The AAA proxyserver 19 analyses the response to determine whether it is the responsethat will be expected from that particular SIM. If the response is asexpected, then the AAA proxy server 19 considers the SIM to beauthenticated with the network 15.

Once the user is authenticated to their home cellular network operator,their terminal 1, 3, 5 is assigned a new IP address by the DCHP server11 of the LAN 13. This IP address is assigned from a pool of such IPaddresses held by the LAN to be assigned to subscribers of their homecellular network operator.

The user is now in a position to access their home cellular network andthe services provided by their home cellular network operator. Suchcommunication between the user and their home cellular network comprisesthe exchange of IP data packets between the user and the cellularnetwork operator.

The embodiment describing this distribution focuses on transmission ofIP data packets from the user terminals 1, 3, 5 to the user's homecellular network 15. Of course the invention is equally applicable tothe transmission of IP data packets in the opposite direction, i.e. fromthe user's home cellular network 15 to the user terminals 1, 3, 5.

In FIG. 1, three cellular networks are available: the user's homecellular network 15 (network “A”), network “B” 23 and network “C” 25.This allows three PDP data channels 27, 29, 31 to be created—PDP datachannel 27 corresponding to network “A” 15, PDP data channel 29corresponding to network “B” 23 and PDP data channel 31 corresponding tonetwork “C” 25. IP data packets are transmitted from the user terminals1, 3, 5 to the user's home network operator 15 through the gatewaytransmitter (BGW-T) 21. IP data packets received in the BGW-T 21 fromthe user terminals are transmitted towards their intended destination(the user's home cellular network 15) by the BGW-T 21. The BGW-T 21includes a plurality of SIM or USIM cards. The SIM or USIM cards allowthe BGW-T 21 to communicate with the networks 15,23,25 by authenticatingthe BGW-T 21 with those networks using information stored on the SIM orUSIM. The SIM or USIM includes data similar to that stored on a SIM orUSIM that would be provided with a user terminal for use with thenetwork, such as an authentication algorithm and a unique key Ki. TheSIMs or USIMs provided on the BGW-T 21 may not be in the physical formof a SIM card. Instead, they could be virtual or simulated SIMs that areimplemented by software.

According to an important feature of the embodiment, the BGW-T 21transmits the IP data packets over multiple PDP data channelsirrespective of the cellular network operator with which the relevantterminal 1,3,5 generating the data packets is registered. This is doneusing multiple PDP contexts, with a different PDP context for eachoperator. Therefore, even though the user holds a subscription to theoperator of network “A” 15, IP data packets sent by the user will berouted through the BGW-T 21 and over network “B” 23 (and hence throughPDP data channel 29) and/or network “C” 25 (and hence through PDP datachannel 31) as well as over network “A” 15 (and hence through PDP datachannel 27).

It should be appreciated that the invention is also applicable to anarrangement where some or all of the networks 15,23 and 25 are notcellular telecommunications networks but are some other type ofcommunications network. For example, one or more of the networks couldbe a satellite communications network. There may be only two networks,or four or more networks. According to the invention, data may betransmitted by the user terminal to its home network (which may or maynot be a cellular telecommunications network) using a combination ofdifferent communications technologies.

The networks 15,23,25 are separate or discrete in the sense that theyhave a separate core for routing data between devices registeredtherewith and/or in the sense that they do not share a radio accessnetwork/base station transceivers. The networks may be operated bydifferent (legal) entities and/or have separate facilities forauthenticating user devices and charging users of devices registeredtherewith for use of the network.

A network address translation (NAT) process is required for IP version 4(IPv4) addresses, to convert those IP addresses assigned to userterminals 1, 3, 5 by the DHCP server 11 of the LAN 13 into the IPaddresses originally allocated to the LAN 13 provider by the operatorsof the cellular networks 15, 23, 25. The NAT process only affects the IPaddresses of the IP data packets that the BGW-T 21 transmits.

Upon receiving IP data packets from the user terminals 1, 3, 5 the BGW-T21 monitors the availability and radio condition of the radio link ofeach of the cellular networks 15, 23, 25 in order to determine the mosteffective routing for the IP data packets. The availability of eachradio link is assessed in terms of the level of the signal given by thevarious different radio links, while the radio conditions of each radiolink are assessed via test signalling sent from the BGW-T 21 through thevarious different radio links. The BGW-T 21 contains a schedulingalgorithm which enables the IP data packets to be distributed and hencetransmitted over different PDP data channels 27, 29, 31 (as will bedescribed in more detail below with reference to FIG. 2) according to,for example, the load or signal strength of each PDP data channel 27,29, 31. By distributing the IP data packets over the plurality ofavailable data channels 27, 29, 31 offered by the operators of multiplecellular networks 15, 23, 25, the user experiences an increase in thebandwidth available without the need for the deployment of extracapacity for each cellular network operator, leading to an increase inthe data capacity available to users in an environment where nodedicated connections to cellular network providers are available incomparison to a system using a single cellular network radio link.Additionally, potential bottleneck situations are avoided, and there isan increase in the bandwidth offered to users without the need fordeploying extra capacity per cellular network 15, 23, 25 operator andthe provision of unified charging through the IP core of the cellularnetwork is available.

The IP data packets distributed and transmitted by the BGW-T 21 overrespective data channels 27,29,31 are received by a gateway receiver(BGW-Rs) 33, 35, 37 (associated with each of the channels) whichcorrespond respectively to the cellular networks 15, 23, 25. Once thedistributed IP data packets are received in the BGW-Rs 33, 35, 37, theyare assembled and routed to the appropriate cellular network 15, 23, 25over dedicated inter-operator links 39, 41 using routers 43, 45, 47contained respectively within the BGW-Rs 33, 35, 37. Each cellularnetwork may comprise a concentrator which acts to re-assemble the IPdata packets into the form they took when originally transmitted by theuser terminal 1, 3, 5 before they were distributed and transmitted bythe BGW-T 21.

For clarity FIG. 1 shows only one concentrator 49 which is associatedwith network “A” 15, but network “B” 23 and network “C” 25 may also havea dedicated concentrator associated with them. If a network does nothave a concentrator associated with it, a user terminal registered withthat network may be able to transmit and receive data packets but willnot be able to use services offered by the operator.

The transmission of the IP data packets from networks 23,25 over links39,41 and the re-assembly of the IP data packets by the concentrator 49completes the transmission of the IP data packets between the user andthe network 15 operator, and the data sent by the user is then able tobe forwarded to the service provider of the particular service asoriginally intended by the user.

For example, the IP data packets may be forwarded by the concentrator 49to the Internet 51 or to IP-based multimedia subsystem (IMS) 53.

An IPsec tunnel (to be described in more detail below) created betweenthe user terminal 1,3,5 and the concentrator 49 may terminate at theconcentrator 49 or at a remote site, using a virtual private network(VPN) service. For example, the IPsec tunnel may be continued using theIMS 53.

IMS is a set of core network servers sitting behind the GGSN of thenetwork operator 15 in the packet switched domain. These servers areintroduced in order to process signalling between end users. The aim ofIMS is to allow users such as mobile telephone network operators toprovide services to their subscribers as efficiently and effectively aspossible. For example, the IMS architecture is likely to support thefollowing communication types: voice, video, instant messaging,“presence” (a user's availability for contact), location-based services,email and web. Further communication types are likely to be added in thefuture. This diverse collection of communication devices requiresefficient session management due to the number of different applicationsand services that will be developed to support these communicationtypes. Session Initiation Protocol (SIP) is used for managing thesesessions.

In order to complete the operation, the concentrator 49 may have toassign a further IP address to the user terminal 1, 3, 5 depending onthe need for access to particular operator-specific services.

IP data packets may of course be transmitted in the reverse direction,that is from the home cellular network 15 to the relevant user terminal1,3,5. Data packets arrive at the concentrator 49 and are thendistributed/sent to each BGW-R 33,35,37 in each cellular network15,23,25 for transmission by respective PDP data channels 27,29,31 toBGW-T 21, where the IP data packets are assembled and transmitted to theappropriate user terminal 1,3,5. It should be noted that, although BGW-T21 is referred to as a “gateway transmitter” and that BGW-Rs 33,35,37are referred to as “gateway receivers” to simplify the aboveexplanation, these components in fact can each perform both transmissionand receiving functions.

In the embodiment the use of the networks 15,23,25 is charged to theentity that operates the access point 7 and LAN 13. If, as in theembodiments described, these components are present on a train, thetrain operator will pay the network operators 15,23 and 25 fortransmission of data. The charge may conveniently be based on a numberof bytes transmitted and received by each operator on behalf of thetrain operator. The number of bytes transmitted/received may be measuredby BGW-T 21 and BGW-Rs 33,35,37 and this information then passed to therelevant network 15,23,25 for charging the train operator.

The train operator may offer free data transmission and access to auser's home cellular network 15 has an incentive for a user of aterminal 1,3,5 to use that particular train operator's transportservice. Alternatively, a fixed charge could be added to a ticketpurchased for travel with the train operator. Alternatively, a mechanismcould be employed for charging a user on a per byte of data transmittedbasis.

Because a user is able to access their home cellular network 15 via theLAN 17, the mechanism by which the IP data packets are transmittedbetween the user's terminal 1,3 and 5 and the users home cellularoperator 15 is transparent to the user, and the user can make use of allthe services provided by its home network operator 15 in apparently thesame manner as is possible with a normal direct cellular radioconnection between the users terminal 1,3 and 5 and the network operator15 (although with improved data rates).

FIG. 2 shows a logical diagram of the IP load balancing method inaccordance with the present invention. The upper panel of FIG. 2corresponds generally to FIG. 1, while the lower panel of FIG. 2 showsthe networking framework according to the Open Systems Interconnection(OSI) reference model, corresponding to the arrangement shown in FIG. 1and the upper panel of FIG. 2. The OSI model divides the functions of aprotocol into a series of layers, each layer only using the functions ofthe layer below and only exporting functionality to the layer above. InFIG. 2, control starts in the application layer of the user terminal 1,3, 5. The application layer provides application services in the userterminal 1, 3, 5 for network software services such as file transfersand email. In order to transfer IP data packets as described above withreference to FIG. 1, control in the terminal 1, 3, 5 is passed down fromone layer to the next in order for control to be passed to the BGW-T 21and distributed over the data channels 27, 29, 31 to the BGW-Rs 33, 35,37 and from the BGW-Rs 33, 35, 37 onto the services 51, 53 to beaccessed by the user. In the services 51, 53 control is passed back upthe hierarchy to the application layer.

In implementing the OSI model with reference to FIG. 2 the physicallayer and layer 2 represent the media section, the network layer(comprising IP and IP security protocols) and the transport layer(comprising transmission control protocol (TCP) and user datagramprotocol (UDP)) represent the transport section and the applicationlayer represents the application section.

In known systems, control has to pass to the physical layer, or at leastto the media section, before the data packets are able to be transportedover the channel. It is a feature of this embodiment that control onlyhas to pass down to the network layer before the data packets can bedistributed and transmitted over the data channels 27, 29, 31, therebyallowing the user data to be transmitted between the user terminal 1, 3,5 and the provider of the services 51, 53 as IP data packets.

As the embodiment allows distribution and transmission of IP datapackets, it will be able to offer a high level of security for thetransmission of user data, as described herein with reference to FIG. 1and FIG. 2, as security is provided at the network layer of the OSImodel, offering protection for IP and upper layer protocols. Atunnelling mechanism such as IP security (IPSec) in tunnel mode orIP-in-IP layer 3 tunnelling protocol (IPinIP) is preferably employed,depending on the security requirements of the user and/or the cellularnetwork operator associated with the concentrator 43, 45, 47.

The IPSec protocol implements network layer encryption andauthentication, thereby providing end-to-end security in the networkarchitecture at the IP layer which can be used by any higher layerprotocol, for example TCP or UDP—both of which reside in the transportlayer (layer 4 of the OSI model). The IPSec protocol can be used in IPv4and IPv6 networks and combines several different security technologiesinto a complete system. In particular, IPSec uses: Diffie-Hellman keyexchange (for deriving key material between peers on a public network),public key cryptography (for signing the Diffie-Hellman exchanges toguarantee the identity of the two parties and avoid man-in-the-middleattacks), bulk encryption algorithms (for encrypting the data), keyedhash algorithms combined with traditional hash algorithms (for providingpacket authentication) and digital certificates (signed by a certificateauthority to act as digital ID cards).

In use, the IPSec protocol defines a new set of headers to be added tothe IP data packets, the new headers being placed before the transportlayer protocol and providing information for securing the payload of theIP data packets. These two new headers are the authentication header(AH), which ensures the authenticity of the data, and the encapsulatingsecurity payload (ESP), which protects the confidentiality, integrityand authenticity of the data. Both AH and ESP can function in eithertransport mode, providing security for upper level protocols byauthenticating and/or encrypting the payload, or tunnel mode, providingsecurity for the whole IP data packet by encapsulating the IP datapacket into a second IP packet.

In the tunnel mode of the IPSec protocol, the original IP data packet isencrypted as shown in FIG. 3. The entire original data packet 55 isencrypted and becomes the payload in a new IP data packet 57. Theconcentrator 49 decrypts the original IP data packet and forwards itonto the intended destination of the data (i.e. the provider of theservices 51, 53).

The IPinIP protocol, as shown in FIG. 4, defines a method whereby an IPdata packet 59 is encapsulated within a second IP data packet 61 andhence carried as a payload. An outer IP header is inserted before the IPdata packet's existing IP header, and the normal IP routing for datapackets is altered by delivering the data packets to an intermediatedestination that would otherwise not be selected by the network part ofthe IP destination address in the original IP header. The outer IPheader contains a source address (SA) and a destination address (DA)which identify the endpoints of the IPinIP tunnel. The SA and DA of theinner IP header identify the original sender and recipient of the datapacket respectively, and the inner IP header is not changed by theencapsulation process or its delivery to the tunnel exit endpoint. Theencapsulator may use any existing IP mechanisms appropriate for deliveryof the encapsulated payload to the tunnel exit endpoint. In particular,the use of IP options is allowed, as is the use of fragmentation unlessthe inner IP header restricts this.

Once the encapsulated IP data packet 61 arrives at the intermediatedestination it is decapsulated, yielding the original IP data packet 59which is then delivered to the destination indicated by the original IPdestination address (i.e. the provider of the services 51, 53).

The embodiment described herein is one way in which IP data packetscould be distributed between a user and a service provider over multipleradio links. It is not intended to, and should not be taken to, limitthe scope of the invention as defined by the following claims. Inparticular, the use of IPSec and IPinIP as the security protocol areintended as examples of the many security protocols for the transmissionof IP data packets that could be incorporated into the presentinvention.

1. A method of transmitting information between a first device and a second device, the method including transmitting respective data packets representing information from one of said devices over different ones of a plurality of communications systems such that the data packets are received by the other of said devices and the information represented thereby may be used.
 2. The method of claim 1, wherein said plurality of communications systems includes at least two wireless communications systems.
 3. The method of claim 1, wherein said communications systems comprise cellular or mobile telecommunications systems.
 4. The method of claim 1, wherein said communications systems comprise GSM or 3G (UMTS) cellular telecommunications systems.
 5. The method of claim 1, wherein said telecommunications systems each have a respective radio access network.
 6. The method of claim 1, including transmitting the data packets representing the information from said one of said devices to a node and, from said node, selectively transmitting said data packets over the plurality of communication systems.
 7. The method of claim 1, wherein said data packets comprise Internet Protocol (IP) data packets.
 8. The method of claim 1, wherein said data packets are transmitted by at least two of said plurality of communication systems by one or more packet data protocol (PDP) channels formed by each of those communications systems.
 9. The method of claim 1, including receiving said data packets at a control portion of each of said communications systems, and forwarding the received data packets by a communications link to a node such that the data packets are received by said other device.
 10. The method of claim 1, including providing each of said data packets with a component indicative of the identity of said one of said devices or said other of said devices for facilitating routing of said data packet.
 11. The method of claim 1, wherein said other device is registerable with one of said communications systems for direct communication therewith.
 12. The method of claim 11, including transmitting to the communication system with which said other device is registered said data packets received by each of said other communication systems.
 13. The method of claim 9, including forming an IPsec channel between said one of the devices and said node for transmission of said data packets therethrough.
 14. The method of claim 1, including authenticating at least one of said devices with the one of the communications systems with which it is registered by means of authentication storage means associated with that device.
 15. The method of claim 14, wherein said authentication storage means comprises a smart card, SIM or USIM.
 16. The method of claim 6, including authenticating said node with each of said communications systems.
 17. The method of claim 16, including authenticating said node with each of said communication systems using respective authentication storage means, such as a SIM or USIM.
 18. The method of claim 1, including monitoring communication characteristics of said communication systems and selectively transmitting said data packets over respective ones of said communications systems in dependence upon the monitored characteristics.
 19. The method of claim 18, wherein the communications systems are monitored in terms of the level of radio signal thereof.
 20. The method of claim 19, wherein the radio signal of each communications system is assessed by test signalling.
 21. Apparatus for transmitting information between a first device and a second device, including means for transmitting respective data packets representing information from one of said devices over different ones of a plurality of communications systems such that the data packets are received by the other of said devices and the information represented thereby may be used.
 22. Apparatus of claim 21, wherein said plurality of communications systems includes at least two wireless communications systems.
 23. Apparatus of claim 21, wherein said communications systems comprise cellular or mobile telecommunications systems.
 24. Apparatus of claim 21, wherein said communications systems comprise GSM or 3G (UMTS) cellular telecommunications systems.
 25. Apparatus of claim 1, wherein said telecommunications systems each have a respective radio access network.
 26. Apparatus of claim 21, including a node to which the data packets representing the information from said one of said devices are transmitted, wherein the node selectively transmits said data packets over the plurality of communication systems.
 27. Apparatus of claim 21, wherein said data packets comprise Internet Protocol (IP) data packets.
 28. Apparatus of claim 21, wherein said data packets are transmitted by at least two of said plurality of communication systems by one or more packet data protocol (PDP) channels formed by each of those communications systems.
 29. Apparatus of claim 21, including a control portion for each of said communications systems for receiving said data packets and for forwarding the received data packets by a communications link to a node such that the data packets are received by said other device.
 30. Apparatus of claim 21, wherein each of said data packets comprises a component indicative of the identity of said one of said devices or said other of said devices for facilitating routing of said data packet.
 31. Apparatus of claim 21, wherein said other device is registerable with one of said communications systems for direct communication therewith.
 32. Apparatus of claim 31, including means for transmitting to the communication system with which said other device is registered said data packets received by each of said other communication systems.
 33. Apparatus of claim 29, including means for forming an IPsec channel between said one of the devices and said node for transmission of said data packets therethrough.
 34. Apparatus of claim 21, including means for authenticating at least one of said devices with the one of the communications systems with which it is registered using authentication storage means associated with that device.
 35. Apparatus of claim 34, wherein said authentication storage means comprises a smart card, SIM or USIM.
 36. Apparatus of claim 26, including means for authenticating said node with each of said communications systems.
 37. Apparatus of claim 36, wherein said authentication means authenticates said node with each of said communication systems using respective authentication storage means, such as a SIM or USIM.
 38. Apparatus of claim 21, including means for monitoring communication characteristics of said communication systems and selectively transmitting said data packets over respective ones of said communications systems in dependence upon the monitored characteristics.
 39. Apparatus of claim 38, wherein the communications systems are monitored in terms of the level of radio signal thereof.
 40. Apparatus of claim 39, including means for generating a test signal to assess the radio signal of each communications system. 